01-25-2013 03:50 PM - edited 01-25-2013 03:52 PM
Qt is a framework for developing cross-platform applications. Cascades is based on Qt. It has it's own GUI classes and other functionality but you can also use everything Qt offers.
Cascades widgets give BB10 applications their native look & feel. You can create GUI using original Qt widgets but it won't look native. It's not possible to mix Cascades & Qt widgets as they have different base classes, different layout methods etc.
More information on Qt can be found here: